Degree Name

Doctor of Philosophy


School of Earth, Atmospheric and Life Sciences


Green roofs are an integral part of the urban forest and are widely used as tools in urban planning for sustainable development. One of the main reasons for the increased focus on green roofs is their social, environmental and economic benefits. Plant selection is a critical component in green roof design, as the vegetation on a roof influences the benefits obtained. Incorrect plant selection also contributes to some of the drawbacks of green roofs, such as the high ongoing cost of maintaining or replacing plants and increased water/fertiliser usage. Biotic facilitative interactions were investigated in this thesis as a means to improve plant growth on a green roof.

A survey across green roofs in Sydney was used to establish the current building practices of green roofs in relation to their vegetation, substrate and physical characteristics. I also attempted to classify green roofs based on their function and investigated whether current designs provided social, environmental and ecological benefits. This was done by scoring roofs based on surveyable attributes associated with each benefit. Of the 29 green roofs surveyed across Sydney, only two roofs scored high in all three categories. Seven roofs scored high in social and environmental benefits, with four scoring high only in ecological benefits. The focus on social benefits was unexpected since most green roofs specified environmental benefits as one of their key aims. The results indicate there might be a shift in the perception of green roofs from being a tool to ameliorate urban physical characteristics to a tool that can enhance concentration, productivity and mental health in the workplace. However, care should be taken so that the focus on social benefits does not come at the expense of the other benefits.

FoR codes (2008)




Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.